Modern lawns require a great deal of care and attention in order to nurture a thick green carpet of grass. Such care includes consistent mowing, watering, and thatching as well as periodic overseeding and fertilization. In addition, it is imperative that a healthy lawn be aerated at least twice a year and, preferably, even more often. Aeration usually entails creating a multitude of closely spaced small holes in the surface of the ground to permit air and oxygen to be absorbed into the soil. The holes also tend to increase moisture penetration into the soil and serve as receptacles for grass seed to prevent the seed from being washed away and to promote germination and growth.
Numerous lawn aeration devices have been available. One such device comprises a large cylindrical drum studded about its periphery with a plurality of short radially extending spikes. The drum is rolled or pulled over the ground and, as it rolls, the spikes are driven into the soil to create shallow holes. While this device is widely used and has proven somewhat successful, it is nevertheless plagued with numerous problems and shortcomings inherent in its design. For example, since the spikes necessarily engage the ground at an angle and are rotated laterally through the soil, significant force is required to penetrate the ground and move the spikes through the dirt. As a result, the drums of these devices generally are relatively large and usually are filled with water or sand or have weight racks to provide sufficient weight to drive the spikes into and through the soil. In addition, the density of spikes on the drum and thus the density of holes the aerator can make in the soil is severely limited since the weight of the device is inherently inadequate to drive more than a few of the spikes at a time into and through the soil. Finally, as each of the spikes of this device is forcibly driven into the soil, it pushes aside the dirt to make room for the spike. This is the action that actually creates the hole; however, it also necessarily compacts and hardens the soil all around the sides of hole. As a result, penetration of air from within the hole into surrounding soil is reduced as is the penetration of moisture. Consequently, the efficiency and advantages of the aeration are reduced.
Another lawn aeration device seeks to address the soil compaction problems of drum and spike aerators by providing hollow spikes that actually pierce the ground and remove a plug of soil to create a hole. During each penetration of the ground, another soil plug is forced upwardly through the hollow spike and the plugs are simply ejected from the spike at its upper extent. While these types of devices, commonly known as pluggers, tend to reduce the compaction of soil around the sides of the holes, they nevertheless do not eliminate it. This is because the soil must still be parted to accommodate the thickness of the walls of the hollow spikes as they pierce the soil. In addition, such hollow spike aerators still require significant force to drive them into and through the soil and thus still require large heavy and cumbersome structures for proper operation. This is because the sliding friction of the soil plug through the hole in the spike is relatively high requiring extra force to drive the plug through the soil. As a result of this extra force, the extracted plugs are usually highly compacted dowell-like plugs, which don't break up and disburse quickly.
Because of their weight, many lawn aerators are motorized. This not only makes them expensive but also renders them difficult to use. When the heavy spiked drums are driven over the ground by their motors, they naturally bump, bounce, and shake about as the spikes are driven into and through the soil. This can create significant fatigue for users of these aerators. Further, the unitary drum construction of these devices renders them very difficult to turn at the end of an aerating run and the drum often must be manually scraped about in an arc to achieve the turn. This is not only cumbersome, it also tends to destroy healthy grass already growing in the lawn and can create an unsightly mess, particularly in moist or wet soil. Slicer aerators having harrow-like discs that create a narrow furrow in the soil are also available. These devices, however, create narrow soil openings that tend to close up very quickly, especially when stepped upon.
Thus, there exists a need for a simple compact aerator that is light, small, and easily pulled or pushed manually across the ground. Such an aerator should require minimum force for piercing and aerating the soil, thus eliminating the need for heavy drums and the like. The spikes of the aerator should be designed to eliminate the compaction of soil common with prior art devices and, in fact, should insure that the soil is actually loosened in the vicinity of each hole to insure maximum aeration and moisture penetration. The device should be easy to use by the common homeowner, inexpensive to purchase, and sufficiently small, light, and easy to roll that it can be attached and pulled behind a standard walk behind lawn mower so that a lawn can be aerated as it is mowed. It is to the provision of such a lawn aerator that the present invention is primarily directed.